12 research outputs found

    Does Seed Sanitization Affect the Plant Rhizosphere Microbiome and Its Ability to Compete with the Human Associated Pathogen, E. coli on Salad Crops?

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    Cultivation of crops in controlled environmental agricultural systems may limit microbial colonization and reduce diversity of the microbial communities. Practices like seed and growth medium sanitization may further impact microbial communities in the mature plant and the plants capacity to limit the growth of pathogens through competition. As humans expand their travels to space, understanding plant growth, health, and development in closed environments will be critical to the success of producing a safe, supplemental food source for astronauts. To determine the persistence of a potential human pathogen in plant growth and development, sanitized and unsanitized seeds from, mizuna (Brassica rapa var japonica) and red romaine lettuce (Lactuca sativa cultivar Outredgeous), were inoculated with Escherichia coli, ATCC 21445, germinated under simulated International Space Station (ISS) environmental conditions and harvested every 7 days until maturity. The persistence of E. coli in the rhizosphere was determined by plating on selective media, real time PCR (Polymerase Chain Reaction) and community sequencing of the rhizosphere communities. E. coli was detected in the crops roots and leaves for several weeks post germination. At day 28, plants from sanitized seeds had significantly higher counts of E. coli on the roots than those from unsanitized seeds. E. coli was also detected on a few uninoculated plants indicating airborne cross contamination among plants in the same growth chamber and suggesting an influence of the natural microbiome on human pathogen survival and persistence in leafy greens. Sequencing analysis revealed variations in composition and diversity between the communities. Understanding the microbial community of the rhizospheric microbiome is only the first step in determining the relationships between plants. Additional studies to include genotypic and phenotypic variations in the plants should be considered to determine if the natural microbes in the rhizosphere may contribute to the health and therefore, safety of the edible plants

    Survival of E. Coli in the Rhizosphere and Phyllosphere of Leafy Greens Grown in Controlled Environment Chambers Under International Space Station Conditions

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    NASA's mission for manned long- duration space exploration drives the research for crop selection to provide a nutritious and safe supplement to an astronaut's diet. Understanding plant growth, health, and the associated microbial communities in closed environments will be critical to the success of this mission. Cultivation of crops in closed controlled environment agricultural systems may limit microbial colonization and reduce diversity of the microbial communities. Furthermore, practices like seed and growth medium sanitization may impact microbial communities in the mature plant and the capacity to limit the growth of food borne pathogens through competition

    How Does Water Delivery System Design Impact the Microbial Load of Salad Crops?

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    In a microgravity setting, such as the environment aboard the International Space Station (ISS), an ideal plant water delivery system is one that can grow edible crops with minimal resource consumption and minimal risk to crew members. There are also concerns associated with the ability to control fluid escape and biofilm formation resulting in potential dangers to systems, crops, or crewmembers. To identify an appropriate system, candidate systems were assembled and operated under simulated ISS environmental conditions (T,CO2,and RH) with red romaine lettuce (Lactuca sativa cultivar 'Outredgeous') as a model crop. Fluid reservoirs and randomly selected planting sites were sampled every seven days until maturity at which point edible plant biomass and root samples were also taken. Heterotrophic bacteria and fungi growth patterns throughout each planting cycle were determined by plate counts on appropriate agar media. The candidate systems were compared to a classic hydroponics system as a control and harvested crops were compared to controls as well as Veggie-grown and market produce. Plants harvested from candidate systems yielded lower average heterotrophic bacteria and fungi per gram of plant mass levels when compared to market and Veggie samples as well as those from the control system. Additional studies to evaluate the system sanitation regimen as well as testing additional crops should be considered to aid in the selection of an ideal system

    A Comparative Study of Gender Representation and Social Outcomes: The Effect of Political and Bureaucratic Representation

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    This article examines whether gender representation of government leadership in the legislative and executive branches improves social equity related to women\u27s social outcomes and how this effect is moderated by the status of democracy. Using a panel data set on 135 OECD and non‐OECD countries from 2005 to 2015, the analysis shows that in non‐OECD countries, political gender representation has a significant, positive impact on female educational attainment and overall gender equality, while bureaucratic gender representation is significant for educational attainment only. For OECD countries, political representation has a consistent effect on educational attainment, labor force participation, and overall gender equality, but there is no evidence of bureaucratic representation. Democratization plays a more critical role in shaping the relationship between institutional representation and women\u27s social outcomes in non‐OECD countries than their OECD counterparts, where gender equality is attributable to broader social, economic, and cultural factors
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